Jump to content
SAU Community

Which Camshafts?

Jamtime

By Jamtime,
in Engines & Forced Induction

 Share

Recommended Posts

TiTAN Grand Master

TiTAN

Posted
Posted
A worked motor with fuel economy and low down drivability, I would like to see that.

RB30 twin cam with 9.2-9.4:1 compression and a GT35 on the side of it, happily plods around in traffic at 1500rpm and gives ~12l/100km city driving

low gown driveability and response are the things to cling to for satisfaction when a combo just doesn't cut the numbers. :cool:

thats why we have twin cam forklift engines because you can have your response and 400kw :P

  • Replies 56
  • Created
  • Last Reply

Top Posters In This Topic

Popular Days

Top Posters In This Topic

Popular Days

Posted Images

Fastrotor Proficient

Fastrotor

Posted
Posted

Hmm interesting topic for sure.

Since head porting is a major part in making big cams work, i think this should be ok to ask in this thread.

I was doing an excel spreadsheet of all the different rb26 head flow numbers i could get my hands on. Some were better than others in the mid range, some a bit better in the top end, to be expected , with differences in machine measurements and job expectations (we don't know they were all for a 'max' flow job etc. Anyhow point is, they were pretty close to each other with nothing HUGE standing out...... EXCEPT ......

Endyne......... and only the exhaust ports..... they were on top in the intake too but only by a small amount. On the exhaust flow results, most topped out at 190 odd cfm ................. there's was around 230+ cfm !!!!!!!!!

Im peeved i seem to have deleted the xlsx spreadsheet else i would post. I guess i could redraw it if anyone was keen to see.

So i'd like to hear from the guru's what they think.

Paul, you being the RS guru, do you have flow numbers for your head please ?

NickR33 Grand Master

NickR33

Posted
Posted

its my understanding that lift and duration have different effects too... duration refers to where in the rev range they are most efficient and increased lift means more airflow at that rpm (which usually means more power)

I've got 260º 10.8mm cams but engine builder reckons he would just go back to standard cams for my car, no real gain to be had in his opinion... but I like the sound lol

livicuru Proficient

livicuru

Posted
Posted
im sorry but yours sounds like one of the worst setups i've ever heard of on a rb

You reckon? well according to my tuner my high mounts with the slighty down sized rear housing come on boost the same time as Rs's but only much harder. Anyway, you have no idea about the overall setup i have and how it compliments the remainding engine mods, hence your narrow statement.

All the best Jam; dont sell your Rs's. :P

JAGR33 Grand Master

JAGR33

Posted
Posted
Lol :) I completley agree with you there. but isnt this guy building a street car...id be willing to sacrifice some top end in a street car for better (in theory) fuel economy and low down drivability.

Hit the nail on the head!!!

Interesting thread, guaranteed to get people fired up!!

I did run 260/9.15 lift poncams with -5's on a built motor, but reverted back to standard cams under instructions from my tuner/mechanic.

One major difference I noticed was pulling into my driveway at home and driving up into the garage (very slight incline). With Poncams my car used to be lethargic. Travelling 10km/h up the driveway my car felt like it needed revs to get into the garage. Once the standard cams were put back in the car it would pretty much idle up the driveway into my garage without a sweat. Now what does this mean? Maybe someone with more technical knowledge than me can explain...

I also felt my on/off boost transition more responsive aswell.

The car made just as much power and similar response (maybe slightly favourable with standard cams) to the Poncams..

Just my 2c.... :O

N1GTR Grand Master

N1GTR

Posted
Posted

Step Zero;

Suits Stock turbos or GTSS, 8000rpm.

Quite a rare crank though, id be suprised if there was many more step zero's than kakimoto's or apexi highdecks.

Anyway, here's a PDF from HKS about this kit:

HKS_Step_Zero.pdf

djr81 Grand Master

djr81

Posted
Posted
Hit the nail on the head!!!

Interesting thread, guaranteed to get people fired up!!

I did run 260/9.15 lift poncams with -5's on a built motor, but reverted back to standard cams under instructions from my tuner/mechanic.

One major difference I noticed was pulling into my driveway at home and driving up into the garage (very slight incline). With Poncams my car used to be lethargic. Travelling 10km/h up the driveway my car felt like it needed revs to get into the garage. Once the standard cams were put back in the car it would pretty much idle up the driveway into my garage without a sweat. Now what does this mean? Maybe someone with more technical knowledge than me can explain...

I also felt my on/off boost transition more responsive aswell.

The car made just as much power and similar response (maybe slightly favourable with standard cams) to the Poncams..

Just my 2c.... :)

It means that longer duration cams work less well at low rpm.

Here is a rough chart showing the durations of stock versus Poncams. Pretty obvious but I don't know what the lift is on the stock cams.

post-5134-1264052933_thumb.jpg

bigslick Collaborator

bigslick

Posted
Posted
All the best Jam; dont sell your Rs's. :blush:

I wish you all the best with your setup too, Jamtime, but your step 0 kit is going to be significantly outpowered by the GT-RS's.

Even the crank in the step 1 wouldn't be able to use them to their potential.

Personally I think -5's make a great street turbo, with a 2.8 stroker even better, but not that one.

R.3.2.G.T.R Grand Master

R.3.2.G.T.R

Posted
Posted (edited)

great thread, been reading other poncam discussions however nothing similar to my setup, rb26 with gt-ss with no headwork but with cam gears, I read -5 guys using the popular 260 9.15mm combo (type b) but not a lot of info with gt-ss

What bout tomei type a which is staggered setup?? Must be of some benefit for smaller turbos.. Type B surely isn't more suitable as it will move the powerband higher.. Is stock cams still best with gt-ss?? Btw car is street driven as a daily

Type A

Duration(IN)- 260°

Duration(EX) - 252°

lift(IN) - 9.15

lift(EX) - 9.15

Type B

Duration(IN) - 260°

Duration(EX) - 260°

lift(IN) - 9.15

lift(EX) - 9.15

Edited by BWRGTR
djr81 Grand Master

djr81

Posted
Posted
great thread, been reading other poncam discussions however nothing similar to my setup, rb26 with gt-ss with no headwork but with cam gears, I read -5 guys using the popular 260 9.15mm combo (type b) but not a lot of info with gt-ss

What bout tomei type a which is staggered setup?? Must be of some benefit for smaller turbos.. Type B surely isn't more suitable as it will move the powerband higher.. Is stock cams still best with gt-ss?? Btw car is street driven as a daily

Type A

Duration(IN)- 260°

Duration(EX) - 252°

lift(IN) - 9.15

lift(EX) - 9.15

Type B

Duration(IN) - 260°

Duration(EX) - 260°

lift(IN) - 9.15

lift(EX) - 9.15

A -5/Poncam B combination will put your maximum torque at 5000rpm or higher depending on what boost you run.

The inlet cam on the type A & B is the same cam.

The exhaust cam on the type A is, in duration, very little different to the stock cam, just with higher lift & very slightly less advance.

Curiously I have seen very few people running -5's with the type A's. I really cannot find a good reason not to use this in place of teh type B's.

Also Tomei will sell you inlet cams with a 252, 256, 260, 270, 280 etc etc durations. You can mix & match & don't have to select a type A or a type B set up.

djr81 Grand Master

djr81

Posted
Posted
LOL, they sure dont feel like it to drive

Should feel like a turbo diesel compared to RB20 powah. :domokun:

At the end of the day it is a turbo motor & when you start running anything like a sniff of boost (1 bar or better) the peak torque is going to move up the rev range. The issue is, I guess, how to make good torque in the midrange (say 4000rpm) without it dieing in the arse up the top end.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • Sean'O
      3D printing fun

      By Sean'O · Posted

      No worries at all 🫡 I think the most satisfying things to make are the little bits that are just impossible to find or they're no longer manufactured. Generally I always try to replace parts with OEM wherever possible. This little project is also great because it'll never see the light of day, but strengthen these brackets so it's not just relying on the little standard screws in the headlight plastic. As soon as I saw the standard brackets and screws I thought, "well I'm not going to install with just the screws, the plastic tabs will just snap off". It's crazy how expensive everything has become yeah. But I suppose that's supply and demand; granted it's a lot easier to get brand new genuine parts these days which is fantastic 😊, I don't have to get totally reamed at the local Nissan dealer ha ha We sure are lucky we have all these manufacturers making parts these days, a few really great Australian companies too like Platinum Racing Products and Fit Mint Automotive, what a time to be alive ❤️ . I've got my eye on the RB26 head by PRP as mine has a very fine hairline crack, so that'll need to be addressed some time in the future. If you have any requests or odd things to make feel free to let me know and I can have a crack at making replacement parts ✌️
    • Duncan
      3D printing fun

      By Duncan · Posted

      Thanks for sharing this, and BTW if your headlights are in good condition they are worth thousands....you might want to consider replacing them with brand new LED ones like this (https://www.nengun.com/78works/full-led-headlights-r32-skyline) and making enough profit to buy a house in Sydney
    • Duncan
      R32 GTS (RB20DE) clogged cat

      By Duncan · Posted

      I'm not sure what sort of shops are nearby, but I'd expect any reasonable exhaust shop could put a cat in it that will not restrict the power that engine makes. Otherwise, if you want to remove it, short lengths that replace the cat are readily available online, search for "de-cat pipes" or "test pipes"  
    • Sean'O
      3D printing fun

      By Sean'O · Posted

      Howdy friends, So another weird one today, I was looking into replacing some broken clips holding the front grille for the R32 GTR (part number 01553-03831), and noticed the brackets which are supposed to hold the grille in place were also missing 😑. I do recall seeing this issue many years ago, but didn't fix it at the time. A quick look on eBay and I was able to find the genuine brackets, along with all the screws which suited the headlights (part numbers 26042-08U05,26092-08U05). Happy days!....  Once they arrived however there was an extra nut in the packaging which implied that there should also be a bolt or a stud, and sure enough, after a bit of searching I found this thread from 2013, and @Ants clearly shows a stud should be present. Reading around a bit more, it's possible the headlights on my car are the "povo pack" headlights as mentioned by @funkymonkey in this thread way back in 2008. This could explain why the studs are missing on my set of headlights. Looking at the headlight diagram I wasn't able to see a suitable part number for the stud itself. The headlight did indeed have a recess that looked like it would accept a stud, but interestingly no thread or anything obvious how the stud would be affixed to the headlight, I suspect it may have been glued in, press fit, or melted into the plastic at the factory. Another member may be able to clarify if they happen to have a genuine set of N1 headlamps. The only thing we have to work with within the recess is a keyway which likely is there to prevent the stud from rotating within the recess. In any case, back to 3D printing, I put together a model which acts like a pug with a friction fit inside this recess, making use of the keyway so it doesn't rotate while tightening a bolt. Printing in TPU will allow it to slightly swell making a nice snug fit without cracking the part. I've designed the adaptor it to accept an 20 mm M6 bolt (stainless with a cap head in my case), as opposed to the standard M5 stud and I made use of the standard galvanised split washer that came with the genuine brackets from Nissan. Once the bolt and screws were all in place, giving the bracket a gentle shake gave the classic "shaking the car" feeling, very solid, which gives me confidence this is going to be able to hold on much better than the janky solution which seems to have been here for the past decade or so. Overall I'm really pleased with how this turned out and maybe there are more people out there running these headlights without a centre stud at all! Link to the freely available model on Printables: Click here Regards, Sean  
    • GabsReDeal
      R32 GTS (RB20DE) clogged cat

      By GabsReDeal · Posted

      Hey everyone, This is my first post apart of the introduction. I tried searching a bit on the forum but couldn't really get a straight answer. I got the car to my mechanic as I felt it being weak. It seems that it was missing on two cylinders due to the injectors. I had all my injectors clean and the car runs much better. The mechanic also confirmed my suspicions that the cat is clogged and needs to be tackled asap. The cat rattles a bit and the hot exhaust warning frequently lights up when driving after getting the injectors clean. In my introduction I was asked about what modification I might be interested in and mentioned a cat delete. From what I was told, this is not really beneficial on the RB20DE and there are more cons than pros.  Could perhaps anyone give some suggestions on what the best course of action would be since the current cat is toast and needs to be removed/replaced anyway? I can also sometimes smell a strong smell of fuel, but I'm not sure if this is related.
×
×
  • Create New...